An automated method of sorting chromosomes is expected to speed genetic research and to allow genetic screening of more pregnancies. Yuet Wai Kan of the University of California at San Francisco described a dual laser, fluorescence-activated sorter in operation at Lawrence Livermore (Calif.) National Laboratory. Two stains are used such that chromosomes have characteristic ratios of blue to yellow fluorescence intensities.

The sorter can distinguish all of the human chromosomes except numbers 10, 11 and 12, Kan says. It also can be used to assign genes rapidly to chromosomes and often to a specific region of a chromosome. For example, the human "homeo box" (see above) has been assigned to the long arm of chromosome 17. Kan says the sorter can be employed to rapidly scan clinical samples for chromosomal abnormalities. It is currently being used to compile a library of DNA segments catalogued by chromosome. This 32-investigator project is directed by Marv Van Dilla of Lawrence Livermore and Larry L. Deaven of Los Alamos (N.M.) National for use in mapping genes, diagnosing genetic diseases and analyzing patient pedigrees.

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